This invention relates to a copier which sets the timing for supplying a copy paper sheet with respect to the motion of its optical scanner on the basis of values of displacements between the position of a copied image with respect to the copy paper sheet and the position of a target image to be copied with respect to the scanned original document measured at two different values of copy magnification during an adjustment period.
When a copier with variable magnification is shipped or checked for maintenance, its paper supply timing is examined in order to correct the displacement between the position of a target image to be copied with respect to the scanned document and the position of the copied image with respect to the copy paper sheet. This correction is conventionally effected by measuring the positions of copied images produced at two different values of magnification as well as the position of the target image which was copied and by determining the value of correction to be made from these measured values. In prior art systems, correction is usually determined either by using these measured values in an equation relating the timing for supplying a copy paper sheet to the displacement between the position of a target image with respect to the scanned original document and the position of the copied image with respect to the copy paper sheet or by consulting a preliminarily prepared table based on the aforementioned equation. Prior art systems relying on such methods are not convenient because calculations are complicated and errors can be easily caused. If the numerical table is too complicated, the operator can easily misread the entries. Moreover, it may require the service of a trained or experienced operator to perform the required adjustments.